Field of the Invention
The invention relates to a photosensitive composition, a protective film, and an element having the protective film. More particularly, the invention relates to a photosensitive composition that can be made into a protective film having good chemical resistance, a protective film formed thereby, and an element having the protective film.
Description of Related Art
In recent years, with the development of the semiconductor industry, liquid crystal displays (LCDs), and organic electro-luminescence displays (OLEDs), and the resulting demand for size reduction, the photolithography process has become a very important topic. In the photolithography process, the desired pattern needs to be finer so as to achieve the goal of size reduction. In general, the finer pattern is formed by performing exposure and development on a positive photosensitive composition having high resolution and high photosensitivity. It should be mentioned that, polysiloxane is generally the main component of the positive photosensitive composition.
In general, the material used as a protective film (such as a planarized film or a cured film) needs to have high heat resistance, high transparency, and high dielectric constant at the same time. Japanese Patent Publication No. 7-98502 discloses a composition containing a novolac resin and a quinone diazide compound. Japanese Unexamined Patent Publication No. 10-153854 and Japanese Laid-Open No. 2001-281853 disclose a composition containing an acrylic resin and a quinone diazide compound. However, the heat resistance of the materials is insufficient, and since the cured film is colored due to the high-temperature treatment of the substrate, the issue of reduced transparency exists.
Moreover, a siloxane polymer is generally used as the material having high heat resistance, high transparency, and high dielectric constant. A quinone diazide compound is formed to provide photosensitivity to the siloxane polymer. For instance, U.S. Patent Application Publication No. 2003-211407 discloses a composition formed by a phenolic hydroxy group-terminated siloxane polymer and a quinone diazide compound; and Japanese Unexamined Patent Publication No. 3-59667 discloses a composition formed by a siloxane polymer such as a phenolic hydroxy group or a carboxyl group formed by a cycloaddition reaction and a quinone diazide compound. However, issues such as coloring readily occur to the compositions when the coating film is whitened or thermally cured due to a large amount of the quinone diazide compound in the compositions or the existence of the phenolic hydroxy group in the siloxane polymer. It should also be mentioned that, the cured films formed by the known compositions above all have the issue of poor chemical resistance and are not suitable for application.
Therefore, how to alleviate the issue of poor chemical resistance of the protective film formed by a photosensitive composition so as to meet the requirements of the current industry is an issue those skilled in the art urgently need to solve.